Thrust bearing arrangement for a deadshaft mounted grinder wheelhead

ABSTRACT

A thrust bearing arrangement is disclosed for a grinder wheelhead of the type that is rotatably mounted on a fixed central shaft, and comprises locating the thrust surfaces on a separate portion of the housing proximate the grinding wheel rather than on the fixed central shaft in order to minimize errors due to thermal expansion of the fixed central shaft.

United States Patent 1 Ryan et al.

[54] THRUST BEARING ARRANGEMENT FOR A DEADSHAF T MOUNTED GRINDERWHEELHEAD Inventors: Merle E. Ryan, William D. Stremel,

both of Dayton, Ohio Assignee: The Bendix Corporation, Southfield,

Mich.

Filed: June 24, 1971 Appl. No.: 156,277

US. Cl ..5l/l68, 308/160 Int. Cl. ..B24b 41/00 Field of Search ..5I/l68;308/DIG. 5,

[56] References Cited UNITED STATES PATENTS 2,735,240 2/l956 Fries et al..5l/l06 MH [451 June 5, 1973 3,247,621 4/1966 Aller ..5l/l68 3,301,613l/l967 De Claire ..308/l22 X FOREIGN PATENTS OR APPLICATIONS 4/1964GreatBritain ..308/l22 6/1950 Great Britain ..308/l22 PrimaryExaminerJames L. Jones, Jr. Attorney-John R. Benefiel, Plante, I-Iartz,Smith & Thompson 57 ABSTRACT 6 Claims, 2 Drawing Figures THRUST BEARINGARRANGEMENT FOR A DEADSHAFT MOUNTED GRINDER WHEELHEAD BACKGROUND OF THEINVENTION The use of a deadshaft mounting of grinder wheelheads in whicha fixed central shaft is used to mount the grinding wheelhead asdescribed in U.S. Pat. No. 3,247,621 assigned to the assignee of thepresent application has led to many advantages, chiefly the eliminationof cantilevering or overhang mounting of the wheelhead hub and theresultant excessive deflection thereof without rendering removal of thegrinding wheel excessively time consuming. In addition, the deadshaftdesign allows placement of the radial bearings directly under the loadfor the most efficient loading thereof.

In this arrangement, the thrusting surfaces were located proximate thewheel as per the conventional practice which dictates minimizing thermalgrowth by placing the thrusting surfaces as close as possible to thewheel.

However, in the deadshaft design, such close placement did not eliminateexcessive thermal growth and accompanying errors and/or excessiveduration of warm-up periods. It has been found that the length of thefixed central shaft as well as its proximity to the radial bearings andthe heat produced therein will cause relatively great movement of thethrusting surfaces relative to the remainder of the housing, the basemounted crush rolls and workpiece mounting spindle, with which thegrinding wheel must be located with great precision for high accuracyform grinding processes.

Therefore, it is an object of the present invention to provide a thrustbearing arrangement for a deadshaft mounted grinding wheelhead whichdoes not produce excessive errors and/or require unduly long warm-upperiods.

SUMMARY OF THE INVENTION These and other objects which will becomeapparent upon a reading of the following specification and claims isaccomplished by locating the thrusting surfaces on a relatively shorthousing structure remotely from the fixed central shaft and the radialbearings mounted therein and adjacent the grinding wheel.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view of a grinding wheeland mounting arrangement in longitudinal section.

FIG. 2 is a detailed view of a portion of the thrust bearings shown inFIG. 1.

DETAILED DESCRIPTION In the following detailed description certainspecific terminology will be utilized for the sake of clarity andspecific embodiments will be described in order to provide a completeunderstanding of the invention, but it is to be understood that theinvention is not so limited and may be practiced in a variety of formsand embodiments.

Referring to the drawings, and particularly FIG. 1, the wheelheadassembly is depicted including a grinding wheel 12 mounted on a hub 14in turn pressed onto tapered surface 16 of a hollow driving shaft 18 bymeans of a collar 20 so as to provide a firm driving connectiontherebetween.

Hollow drive shaft 18 has a drive pulley 22 fixed to its other end bymeans of a retainer 24 so as to provide a driving engagement with a beltdrive (not shown) to rotate the grinding wheel 12 during grindingoperations.

A bull gear 26 is also fixed to the hollow shaft 18 to provide a drivingsurface for a slow speed drive (not shown) to rotate the grinding wheel12 during crush dressing operations.

The hollow shaft 18 is supported radially by means of a fixed centralshaft 28, supported at one end on door structure 30 and tapered cap 32,bolted to both elements, and at the other end by housing structure 34bolted thereto.

The hollow shaft 18 is supported on the fixed central shaft 28 by meansof a hydrostatic bearing arrangement including a pair of series ofcircumferentially spaced pockets 36 formed in the fixed central shaft 28and supplied with a fluid from a source (not shown) via central passage38, radial passage 40, and orifices 42. Fluid passing out of the pockets36 past the clearances between the fixed central shaft 28 and the hollowdrive shaft 18 is collected in annular spaces 44, 46, and 48 and passesinto return passages 50, 52, and 54 to be returned to the sump (notshown) via passage 55. The fluid contained in these pockets provides alow friction support for rotating of the wheelhead assembly 10 thereonas is well known in the art.

The hollow drive shaft 18 is positioned against axial loads by means ofa separate thrust bearing arrangement 56 according to the presentinvention.

This arrangement includes a thrust ring member 58 fixed to housingstructure 60 so as to be securely supported against lateral loads.

The thrust ring 58 includes an annular portion 62 (FIG. 2) disposedextending around the exterior of hollow drive shaft 18 between a pair ofthrust surfaces 64, 66 of the wheelhead assembly 10 formed by shoulders68, 70 on the hollow drive shaft 18 and hub 22, respectively.

A series of circumferentially spaced pockets 72 are formed in theannular portion 62 facing the thrust sur' faces 64, 66 and are suppliedwith fluid via radial passage 74 and a series of axial passages 76containing metering orifices 78. Flow past clearances between theannular portion 62 and other thrust surfaces 64, 66 is collected inannular spaces 80, 82 and 84 in turn collected in passage 55 for returnto the sump (not shown).

As the thrust surfaces are disposed proximate the wheel 12, a minimallength of the drive shaft 18 is subject to thermal expansion whichresults in axial displacement of the grinding wheel 12 relative to thethrust bearing 56.

Furthermore, the fixed thrust absorbing structure itself, i.e., thethrust ring 58, is of relatively narrow dimension so that thermalexpansion thereof also is minimal.

Finally, the thrust bearing arrangement 56 is remotely located withrespect to the radial bearings so that the effect of heat builduptherein on the thrust bearing arrangement is minimized.

Accordingly, the advantages of a deadshaft design are realized by theuse of the present invention without entailing the penalty of thermalgrowth errors and/or excessive warm-up periods.

Many variations are of course possible within the scope of theinvention. For example, while the use of hydrostatic bearings is highlyadvantageous in this context it would of course be possible to utilizemechanical bearings as described in the aforesaid US. patent.

What is claimed is:

l. A grinding wheel mounting arrangement comprismg:

a grinding wheel;

a hollow drive shaft connected to said grinding wheel;

a fixed central shaft disposed within said drive shaft;

3. The arrangement of claim 1 wherein said fixed central shaft is fixedat both ends.

4. A mounting arrangement for a member to be rotated comprising:

a hollow drive shaft connected to said member;

a fixed central shaft disposed within said drive shaft;

bearing means rotationally supporting said drive shaft on said fixedcentral shaft;

thrust bearing means including a fixed thrust member disposed around theexterior of said drive shaft adjacent said member and cooperating withthrust surfaces on said drive shaft to restrain axial movement thereof.

5. The arrangement of claim 4 wherein said thrust member includes anannular portion extending radially between a pair of shoulders fixed tosaid drive shaft.

6. The arrangement of claim 4 wherein said member is a grinding wheel.

1. A grinding wheel mounting arrangement comprising: a grinding wheel; ahollow drive shaft connected to said grinding wheel; a fixed centralshaft disposed within said drive shaft; bearing mans rotationallysupporting said drive shaft on said fixed central shaft; thrust bearingmeans including a fixed thrust member disposed around the exterior ofsaid drive shaft proximate to said grinding wheel and cooperating withthrust surfaces on said drive shaft to restrain axial movement thereof.2. The arrangement of claim 1 wherein said thrust member includes anannular portion extending radially between a pair of Shoulders fixed tosaid drive shaft.
 3. The arrangement of claim 1 wherein said fixedcentral shaft is fixed at both ends.
 4. A mounting arrangement for amember to be rotated comprising: a hollow drive shaft connected to saidmember; a fixed central shaft disposed within said drive shaft; bearingmeans rotationally supporting said drive shaft on said fixed centralshaft; thrust bearing means including a fixed thrust member disposedaround the exterior of said drive shaft adjacent said member andcooperating with thrust surfaces on said drive shaft to restrain axialmovement thereof.
 5. The arrangement of claim 4 wherein said thrustmember includes an annular portion extending radially between a pair ofshoulders fixed to said drive shaft.
 6. The arrangement of claim 4wherein said member is a grinding wheel.